1. Field of the Invention
The present invention relates to a photosensitive composition for electrophotography. More particularly, it relates to a novel sensitizer which improves the sensitivity of a photosensitive composition when it is added to an organic photoconductive compound.
2. Description of the Prior Art
Heretofore, inorganic compounds such as selenium, zinc oxide, cadmium sulfide or the like, have been used as photosemiconductors for electrophotography. Recently, organic photosemiconductors (organic photoconductive compounds) such as the polyvinyl carbazoles have been considered. However, these organic photosemiconductors usually have low sensitivity. Accordingly, it is necessary to increase their sensitivity by adding a sensitizer in order to make them practical for electrophotographic use. Sensitizers are usually classified into certain groups depending upon the sensitizing mechanism involved. Typical groups are: sensitizers which impart sensitivity because of the presence of absorption bands in the sensitizer, such as dyes; and sensitizers which impart sensitivity by charge transfer interaction with an organic photosemiconductor. The latter is especially superior to the former from the viewpoint of photoresistance. However, practical sensitivity has not been attained by using these conventional sensitizers.
Consequently, it would be most desirable to have a sensitizer, especially from the second class mentioned above, with sufficient sensitivity to enable use as in electrophotography.